Andrew Zambazos
142 lines
3.8 KiB
JavaScript
142 lines
3.8 KiB
JavaScript
/*
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* Copyright (C) 2022 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGE.
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*/
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class IterableWeakSet
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{
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constructor(items = [])
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{
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this._wrappers = new Set;
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this._wrapperForItem = new WeakMap;
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for (let item of items)
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this.add(item);
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}
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// Public
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get size()
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{
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let size = 0;
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for (let wrapper of this._wrappers) {
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if (wrapper.deref())
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++size;
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}
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return size;
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}
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has(item)
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{
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let result = this._wrapperForItem.has(item);
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console.assert(Array.from(this._wrappers).some((wrapper) => wrapper.deref() === item) === result, this, item);
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return result;
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}
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add(item)
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{
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console.assert(typeof item === "object", item);
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console.assert(item !== null, item);
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if (this.has(item))
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return;
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let wrapper = new WeakRef(item);
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this._wrappers.add(wrapper);
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this._wrapperForItem.set(item, wrapper);
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this._finalizationRegistry.register(item, {weakThis: new WeakRef(this), wrapper}, wrapper);
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}
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delete(item)
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{
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return !!this.take(item);
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}
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take(item)
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{
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let wrapper = this._wrapperForItem.get(item);
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if (!wrapper)
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return undefined;
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let itemDeleted = this._wrapperForItem.delete(item);
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console.assert(itemDeleted, this, item);
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let wrapperDeleted = this._wrappers.delete(wrapper);
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console.assert(wrapperDeleted, this, item);
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this._finalizationRegistry.unregister(wrapper);
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console.assert(wrapper.deref() === item, this, item);
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return item;
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}
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clear()
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{
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for (let wrapper of this._wrappers) {
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this._wrapperForItem.delete(wrapper);
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this._finalizationRegistry.unregister(wrapper);
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}
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this._wrappers.clear();
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}
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keys()
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{
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return this.values();
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}
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*values()
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{
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for (let wrapper of this._wrappers) {
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let item = wrapper.deref();
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console.assert(!item === !this._wrapperForItem.has(item), this, item);
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if (item)
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yield item;
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}
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}
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[Symbol.iterator]()
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{
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return this.values();
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}
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copy()
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{
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return new IterableWeakSet(this.toJSON());
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}
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toJSON()
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{
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return Array.from(this);
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}
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// Private
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get _finalizationRegistry()
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{
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return IterableWeakSet._finalizationRegistry ??= new FinalizationRegistry(function(heldValue) {
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heldValue.weakThis.deref()?._wrappers.delete(heldValue.wrapper);
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});
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}
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}
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